3G (the third generation) radio mobile communication evolves successively in which new requirements are introduced continuously to achieve low cost and high performance. In Release 5 (R5) and Release 6 (R6), High Speed Downlink Packet Access (HSDPA) and High Speed Uplink Packet Access (HSUPA) are respectively introduced for the purpose of increasing the throughput of a single cell and the peak rate of single user equipment (UE) of the system by fully taking advantages of the limited radio resource, more rapidly responding to the request by UE and reducing the delay.
HSUPA is the technology by which Wideband Code Division Multiple Access (WCDMA) system improves the uplink transmission capability, wherein it is mainly introduced three technologies: Hybrid Automatic Repeat Request (HARD) of the physical layer; rapid scheduling based on Node B (base station); short frame transmission of 2 ms TTI (Transmission Timing Interval). The performance of HSUPA system significantly exceeds that of the traditional WCDMA in uplink service transmission, in which the system capability is increased by about 50%-70%, the delay of end-to-end packet is reduced by 20%-55%, and the user packet call traffic is increased by about 50%.
The WCDMA system employing HSUPA technology comprises a radio network controller (RNC), Node B and a UE. By measuring uplink load of each cell and the channel quality of the UE duly, Node B determines the authority distributed to each UE according to the measured uplink load of the cell, the current channel quality of the UE, and the scheduling request information of the UE as well as the priority of the UE, then transmits the corresponding scheduling instruction to the corresponding UE which, according to the authority of Node B, selects appropriate transmission format combination from the E-TFC (Enhanced Transport Format Combination) table which is preconfigured to the UE by RNC, so as to transmit uplink E-DCH (Enhanced Dedicated Channel) data to Node B.
In HSUPA, the authority can be transmitted to the UE via the following three ways:
1. During establishing the radio link, the serving Node B distributes initial authority which is transmitted to the UE via RNC. The authority is an absolute authority;
2. The serving Node B transmits the authority to the UE via E-DCH absolute grant channel (E-AGCH, E-DCH) with the authority being an absolute authority;
3. The serving Node B and the non-serving Node B transmit the authority to the UE via E-DCH relative grant channel with the authority being a relative authority, as shown in FIG. 1; the serving Node B can transmit UP (the authority for increasing one step length), DOWN (the authority for decreasing one step length) and HOLD (keeping the current authority unchanged), and the non-serving Node B can transmit DOWN and HOLD wherein the particular step length is determined by the configuration of RNC.
The relationship between E-RGCH channel time and the time of the primary common control physical channel (P-CCPCH) and dedicated physical channel (DPCH) is shown in FIG. 2. As for the serving Node B, the UE with 10 ms E-DCH TTI has the following equation:
      τ                  E        ⁢                  -                ⁢        RGCH            ,      n        =      5120    +          7680      ×              ⌊                                            (                                                τ                                      DPCH                    ,                    n                                                  /                256                            )                        -            70                    30                ⌋            
The UE with 2 ms E-DCH TTI has the following equation:
      τ                  E        ⁢                  -                ⁢        RGCH            ,      n        =      5120    +          7680      ×              ⌊                                            (                                                τ                                      DPCH                    ,                    n                                                  /                256                            )                        +            50                    30                ⌋            
For non-serving Node B, τE-RGCH=5120 chips.
wherein, τE-RGCH,n is the drift of E-RGCH respective to PCCPCH channel with the unit of chip, and τDPCH,n is the drift of DPCH respective to PCCPCH channel with the unit of chip, which is in the range of 0.38144 and has the step length of 256 chips.
By the above description, there is no strict requirement on time for the initial authority and the authority granted to UE via E-AGCH. As for the authority value granted to UE via E-RGCH which is the LUPR of the same HARQ process with respect to the previous HARQ round-trip-time (HARQ_RTT), a strict time requirement is imposed on the time of the schedule wherein this HARQ process is used in the previous round-trip-time (RTT) to schedule the index value in the quantization table corresponding to the power drift between the enhanced dedicated physical data channel (E-DPDCH) for data transmission and the dedicated physical control channel (DPCCH). According the relationship between the time sequence of E-RGCH and the time sequence of PCCPCH and downlink DPCH (as shown in FIG. 2), E-RGCH has 5 time points of transmission in each frame which are respectively corresponding to 2nd slot, 5th slot, 8th slot, 11th slot, and 14th slot of PCCPCH, therefore the scheduling interval generally is 2 ms so as to ensure that all HARQ processes of all UEs can schedule E-RGCH.
In the existing scheduling method, the scheduling happens every 2 ms, therefore it is required to calculate the cell load and the load currently occupied by individual UEs so as to calculate the rise over thermal (RoT) of the cell usable by the Serving E-DCH, then the RoT resource of the cell is assigned to among the Serving UEs based on specific scheduling algorithm, thereafter it is determined to transmit an appropriate scheduling instruction. All of these operations must be completed in a given time period and the scheduling algorithm is comparatively complex.
In conclusion, it is necessary to provide a technology solution which is able to reduce the complexity of HSUPA scheduler.